Loving my new 17mm Ethos

[Rodstar (Rod)]

Hi all,

Having poo-pooed the idea of getting another Ethos for some time now, I finally took the plunge and picked up a 17mm Ethos from Bintel at SPSP last weekend. And I am glad I did!

I remain a big fan of Nagler eyepieces. My workhorse for many years has been the 20mm T5. It provides a good compromise in most conditions in the Mary Rose. With Paracorr, which is how I always observe to remove any coma, the 20T5 provides a magnification of 146x, with an Exit Pupil of 3.5 and a TFOV of 32.4 arc minutes. This provides an excellent context in which to observe most objects other than the very large ones, for which I move to the 31mm "Terminagler". The only downside of the 20T5 is the somewhat tight eye relief of 12mm, which I don't mind but others do especially if they observe with glasses.

So what about the 17E? Well I took the opportunity offered by John Gerkin (Xstream) and Anna Novak (Anna) at SPSP to try their 17E and 21E in the Mary Rose. Both eyepieces were fabulous, but what particularly struck me was that the additional magnification of the 17E brought out a lot more detail in the deep sky targets, with a darker background sky. At the same time, it still yielded a good TFOV, and the magnification was not so high as to render the EP unusable in average conditions. In short, this was EVEN BETTER than the 20T5!

The stats of the 17E in the Mary Rose (all with Paracorr): Magnification 172x , Exit Pupil 3mm, TFOV 34.8 arc minutes. What is noticeable is that the TFOV is larger than the 20T5, whilst ramping up the magnification and contrast a notch. As with all Ethoi, it has an ER of 15mm which is just a little more comfortable for everyone.

The results have been great. Both at SPSP and again last night whilst observing in my backyard on the NSW Central Coast, I enjoyed razor sharp images at the higher power and better contrast of the 17E without any concern that the conditions may not be able to support the magnification. I was able to draw out excellent detail in the Homunculus last night under suburban skies, and it frames numerous OCs and Globs beautifully.

The 17E has become my new workhorse!

Will I get the 21E as well? Probably not. The 17E and the 31T5 are parfocal, such that if I really want a larger FOV of the night sky for the largest objects, the 31T5 will be fine, especially under dark skies where the 31T5 comes into its own without having to fight against lighter skies.

I am a big advocate of keeping things simple. Don't have too many eyepieces. Just have a few fantastic eyepieces, and make the most of them. My advice is to work out the sweet spot for your scope, and get yourself the highest quality wide field eyepiece at that focal length that you can afford.

[Satchmo]

Nice report , Rod. 3mm pupil is certainly in a sweet spot for deep sky observing and the larger true field with the Ethos making it even more appealing . A 10mm Ethos would probably complete a basic 3 eyepiece set .

[Allan]

Very nice! I have looked through all the Ethos and found the 17 was the most comfortable to use, and easiest one to see the field stop. I know a lot of people buy Ethos because the field stop disappears, it's certainly hard to see in the 21.

I like your advice too, which I have heard time and again. If you can afford just one good eyepiece, get it at 3mm exit pupil.

[barx1963 (Malcolm)]

Rod
Welcome to the 17E fan club!

My 17E will quite often be popped in the focuser at the start of a session to align the Argo and stay there the entire time. I don't use a Paracorr even though I am at f5 in the 20"as I like 150x and I really don't notice the coma.
At the SV camp in March last year I lent it to Paddy to use in his 16" and he had one in his case within a week. ( and sent me a PM saying I had cost him a lot of money!)
As you can see in my sig I have the 5 Ethoi from 8 to 21, but the 17 is just a killer EP. I get a slightly larger exit pupil with no Parracor but it is still very nice.
On Friday night had had a look at the Homunculus and the detail at 150x was awesome.

Cheers

Malcolm

[el_draco (Rom)]

Has anybody used ethos eyepieces with a powermate? I am curious about flexure in the combination.

[Allan]

Originally Posted by el_draco

Has anybody used ethos eyepieces with a powermate? I am curious about flexure in the combination.

No flexure, as long as you have a good focuser, and optically the combination is still very good. But it is a weird, long looking train sticking out of the focuser, not to mention the weight. Personally I just stick to using eyepieces only, I hardly ever use my Powermate.

[Renato1 (Renato)]

Originally Posted by Satchmo

Nice report , Rod. 3mm pupil is certainly in a sweet spot for deep sky observing and the larger true field with the Ethos making it even more appealing . A 10mm Ethos would probably complete a basic 3 eyepiece set .

Interesting. I seem to be out of whack with a lot of people here. While I find a 3mm exit pupil indeed best for faint open clusters (and there are areas of the sky where they abound), time after time I've found the 2mm exit pupil to be superior on galaxies and very faint nebula. I just can't see them as easily at either 2.5mm or 1.5mm exit pupils at a dark site.

Regards,
Renato

[Allan]

Renato you are correct, but have missed the point of the statement. As an all round deep sky eyepiece, you can't beat a 3mm exit pupil. As you point out, 3mm is not ideal for detecting faint detail in galaxies. But that is a separate issue.

[ausastronomer (John Bambury)]

Nice pickup Rod. The 17mm Ethos gets 90% of focuser time in the 30" SDM when we are at Coona.

Cheers
John B

[Rodstar (Rod)]

Thanks Mark, Allan, Malcolm and John. Sounds like we have a consensus about this eyepiece!

[Camelopardalis (Dunk)]

The 17 Ethos is probably my favourite eyepiece...it's my "without fail" eyepiece with my C11

[Rick Petrie]

Great comments Rod. Congrats on your purchase.
I too love my 17E which I have had for about 3years now. Gave mine a good workout just recently at Bretti under nice dark skies. You've probably looked through mine up at the PC, not sure?
You will definitely get the most out of it in the Mary Rose. Cheers Rick.

[Rodstar (Rod)]

Thanks for your comments Rick and Dunk. I can't understand why more people do not rave about the 17E!

[AG Hybrid (Adrian)]

nice post and read. Makes me wants a 17mm Delos.

[Camelopardalis (Dunk)]

Originally Posted by Rodstar

I can't understand why more people do not rave about the 17E!

Probably because many newt owners want the bigger, badder 21mm version, and the 13mm and don't see where the 17 fits in. It's underrated. I appreciate the "symmetry" of it having half the field area, and being parfocal with, the 31T5 (which I don't yet own ). What a combination

For me, the 17mm works great with my C11 for about 165x, so on the not-so-great nights it's a workhorse for planetary and globs. Amongst many others, Omega Centauri is just spectacular in it

[Don Pensack]

Noticing, as I've gotten older, that the 31 Nagler had a large enough exit pupil in my scope to enter into the "astigmatism zone", I wanted an eyepiece with almost as large a true field, so I ended up with the 21 Ethos.
It's outside the "astigmatism zone" of my nighttime-dilated pupil, yet still has a low-enough power and large-enough field to be used as a low-power eyepiece.
That meant the 17 Ethos was a bit too close in magnification to make it practical, and I found the jump to the 13 Ethos to be about ideal.
So a 21-13-8 Troika was where I started. I added the 10mm, 6mm, and 4.7mm later on to sort of "complete the set", so to speak.
But, had the 31 Nagler been sharp for my eyes, then the 17 Ethos would have been a grand next step, followed by the 10 and 6mm.
When I was last at Coonabarabran, I was impressed with just how good the 17mm focal length worked in the 18" dob I spent some time with. When I got home, I calculated the magnification to be exactly the same as the 13mm in my own scope, which also happens to be my most-used eyepiece.
So I hear you when you say that the 17 Ethos is just right. There is always one magnification and field of view that just kind of "clicks" with each observer.

[Rodstar (Rod)]

Hey Don, nice website you have got there! Some good specials....

Yep, I totally understand your comments about the 31T5 as it applies to your eyes, and the knock-on effect so far as the EP line-up goes.

And Dunk - I was in that frame of mind that you describe - having something at that 20/21mm focal length meant I did not even consider a 17mm eyepiece for years!

Sadly the air is quite unsteady in my neighbourhood - I live low down between a waterway and a hill, and the air tends to swirl a bit. The result is poor seeing a lot of the time. That being the case, my EP Line-up is biased towards lower power. Sadly the 13E does not get a huge amount of use from the backyard - it is more useful however when I head out to darker skies.

I have thought about getting the 10E as well, but I already have a 9T6, and for the 2 or 3 times each year I use the 9T6, it's is probably a tad over the top to get a 10E as well.

[Renato1 (Renato)]

Originally Posted by Allan

Renato you are correct, but have missed the point of the statement. As an all round deep sky eyepiece, you can't beat a 3mm exit pupil. As you point out, 3mm is not ideal for detecting faint detail in galaxies. But that is a separate issue.

Thanks Allen,
I guess it all depends what one is into. I must admit that when using my Maks nowadays, I tend to go for a 3mm exit pupil. But in my galaxy hunting days of many years ago with my dob, while I really liked my then 3mm exit pupil eyepiece (Meade 14mm Ultrawide) I just kept going back to my 2mm exit pupil eyepiece most of the time (9mm Nagler) - mainly because there a thousands more galaxies than the rest of the DSOs.
Cheers,
Renato

[Steffen]

When I use my Mak the largest exit pupil is 1mm. Occasionally I'll go 2mm, but I usually stay below 1mm. The fun (i.e. pushing the Mak's capabilities) starts at 0.5mm.

Seeing galaxies requires mostly aperture and not a lot of precision. A silvered bath tub will show faint galaxies.

(exaggerated to make a point, of course)

(disclaimer above included for people who are easily offended )

(smiley included for people who lack a sense of humour)

Cheers
Steffen.

[Renato1 (Renato)]

Originally Posted by Steffen

When I use my Mak the largest exit pupil is 1mm. Occasionally I'll go 2mm, but I usually stay below 1mm. The fun (i.e. pushing the Mak's capabilities) starts at 0.5mm.

Seeing galaxies requires mostly aperture and not a lot of precision. A silvered bath tub will show faint galaxies.

(exaggerated to make a point, of course)

(disclaimer above included for people who are easily offended )

(smiley included for people who lack a sense of humour)

Cheers
Steffen.

Hi Steffen,
Yes, but sometimes one wants to see something bright in a small MAK. Eta Carina and the Sagittarius starfields do look nice for a few minutes of viewing with a 56mm (4.6mm exit pupil) or 50mm eyepiece, especially with a Skyglow filter attached.
Cheers,
Renato